SimpleXMLElement::addChild()

(PHP 5 >= 5.1.3, PHP 7)

Adds a child element to the XML node

说明

publicSimpleXMLElement::addChild(string $name[,string $value[,string $namespace]]): SimpleXMLElement

Adds a child element to the node and returns a SimpleXMLElement of the child.

参数

$name: The name of the child element to add.
$value: If specified, the value of the child element.
$namespace: If specified, the namespace to which the child element belongs.

返回值

TheaddChildmethod returns a SimpleXMLElement object representing the child added to the XML node.

范例

Note:
Listed examples may includeexample.php, which refers to the XML string found in the first example of the basic usage guide.

Example #1 Add attributes and children to a SimpleXML element

<?php
include 'example.php';
$sxe = new SimpleXMLElement($xmlstr);
$sxe->addAttribute('type', 'documentary');
$movie = $sxe->addChild('movie');
$movie->addChild('title', 'PHP2: More Parser Stories');
$movie->addChild('plot', 'This is all about the people who make it work.');
$characters = $movie->addChild('characters');
$character  = $characters->addChild('character');
$character->addChild('name', 'Mr. Parser');
$character->addChild('actor', 'John Doe');
$rating = $movie->addChild('rating', '5');
$rating->addAttribute('type', 'stars');
 
echo $sxe->asXML();
?>

以上例程的输出类似于：

<?xml version="1.0" standalone="yes"?>
<movies type="documentary">
 <movie>
  <title>PHP: Behind the Parser</title>
  <characters>
   <character>
    <name>Ms. Coder</name>
    <actor>Onlivia Actora</actor>
   </character>
   <character>
    <name>Mr. Coder</name>
    <actor>El Act&#xD3;r</actor>
   </character>
  </characters>
  <plot>
   So, this language. It's like, a programming language. Or is it a
   scripting language? All is revealed in this thrilling horror spoof
   of a documentary.
  </plot>
  <great-lines>
   <line>PHP solves all my web problems</line>
  </great-lines>
  <rating type="thumbs">7</rating>
  <rating type="stars">5</rating>
 </movie>
 <movie>
  <title>PHP2: More Parser Stories</title>
  <plot>This is all about the people who make it work.</plot>
  <characters>
   <character>
    <name>Mr. Parser</name>
    <actor>John Doe</actor>
   </character>
  </characters>
  <rating type="stars">5</rating>
 </movie>
</movies>

参见

SimpleXMLElement::addAttribute() Adds an attribute to the SimpleXML element
Basic SimpleXML usage

To complete Volker Grabsch's comment, stating :
"Note that although addChild() escapes "<" and ">", it does not escape the ampersand "&"."
To work around that problem, you can use direct property assignment such as :
<?php
$xmlelement->value = 'my value < > &';
// results in <value>my value &lt; &gt; &amp;</value>
?>
instead of doing :
<?php
$xmlelement->addChild('value', 'my value < > &');
// results in <value>my value &lt; &gt; &</value> (invalid XML)
?>
See also: http://stackoverflow.com/questions/552957 (Rationale behind SimpleXMLElement's handling of text values in addChild and addAttribute)
HTH

Here is a class with more functions for SimpleXMLElement :
<?php
/**
 *
 * Extension for SimpleXMLElement
 * @author Alexandre FERAUD
 *
 */
class ExSimpleXMLElement extends SimpleXMLElement
{
  /**
   * Add CDATA text in a node
   * @param string $cdata_text The CDATA value to add
   */
 private function addCData($cdata_text)
 {
  $node= dom_import_simplexml($this);
  $no = $node->ownerDocument;
  $node->appendChild($no->createCDATASection($cdata_text));
 }
 /**
  * Create a child with CDATA value
  * @param string $name The name of the child element to add.
  * @param string $cdata_text The CDATA value of the child element.
  */
  public function addChildCData($name,$cdata_text)
  {
    $child = $this->addChild($name);
    $child->addCData($cdata_text);
  }
  /**
   * Add SimpleXMLElement code into a SimpleXMLElement
   * @param SimpleXMLElement $append
   */
  public function appendXML($append)
  {
    if ($append) {
      if (strlen(trim((string) $append))==0) {
        $xml = $this->addChild($append->getName());
        foreach($append->children() as $child) {
          $xml->appendXML($child);
        }
      } else {
        $xml = $this->addChild($append->getName(), (string) $append);
      }
      foreach($append->attributes() as $n => $v) {
        $xml->addAttribute($n, $v);
      }
    }
  }
}
?>

In the docs for google sitemaps it is required an element for mobile sitemaps that looks like this: <mobile:mobile/>
I used some time to figure out how to make it, but it is quite simple when understood.
$mobile_schema = 'http://www.google.com/schemas/sitemap-mobile/1.0';
//Create root element
$xml_mobile = new SimpleXMLElement('
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:mobile="'.$mobile_schema.'"></urlset>
');
//Add required children
$url_mobile = $xml_b_list_mobile->addChild('url');
$url_mobile->addChild('loc', 'your-mobile-site-url');
$url_mobile->addChild('mobile:mobile', null, $mobile_schema);
For this to work properly the attribute xmlns:mobile must be set in the root node, and then used as namespace(third argument) when creating the mobile:mobile child with null as value.

Note that although addChild() escapes "<" and ">", it does not escape the ampersand "&".
So addChild() is unsuited to handle user-defined input!
Instead, you will have to replace all "&" with "&amp;" before calling addChild().
Or, use htmlspecialchars() which also replaces other characters, but won't do any harm as addChild() won't replace those again.

Want to continue the ampersand (&) chain problem.
Sometimes, you would want to assign (=) addChild.
This trick will helps you to do this.
<?php
$webOrders = new SimpleXMLElement('<?xml version="1.0"?><WebOrders></WebOrders>');
$webOrder = $webOrders->addChild('WebOrder');
$product = $webOrder->addChild('Product');
$product[0] = 'T&M';
$product->addAttribute('price', 19.99);
$product->addAttribute('qty', 2);
var_dump($webOrders->asXML());
?>
OUTPUT would be:
<?xml version="1.0" encoding="UTF-8"?>
<WebOrders>
  <WebOrder>
    <Product price="19.99" qty="2">T&amp;M</Product>
  </WebOrder>
</WebOrders>

Here's my solution for creating XML from Multidimensional Array. 
<?php
//DATA 
    $xmlDAta = array(
      array(
        "name" => "nameVal",
        "value" => "valVal",
        "css"  => "cssVal"
      ),
      array(
        "name" => "name1Val",
        "value" => "val1Val",
        "css"  => "css1Val"
      ),
      "tname" => array(
        array(
          "iTname"  => "iTname",
          "iTname2" => "iTname1",
          "iTname2" => "iTname2",
          "iTbname3" => array(
            "iiTbname" => "tbName",
            "iiTbname1" => "tbName1",
          ),
        ),
      ),
      "tdata" => "otheerDAta"
    );
  /**
   * Create XML using string or array
   *
   * @param mixed $data input data
   * @param SimpleXMLElement $xml
   * @param string $child name of first level child
   *
   * @return adding Xml formated data into SimpleXmlElement
   */
function data2XML(array $data, SimpleXMLElement $xml, $child = "items")
  {
    foreach($data as $key => $val) {
      if(is_array($val)) {
        if(is_numeric($key)) {
          $node = $xml->addChild($child);
          $nodes = $node->getName($child);
        } else {
          $node = $xml->addChild($key);
          $nodes = $node->getName($key);
        }
        $node->addChild($nodes, self::data2Xml($val, $node));
      } else {
        $xml->addChild($key, $val);
      }
    }
  }
//Use 
    $xml  = new SimpleXMLElement("<root/>");
    Util::data2XML($xmlDAta, $xml, "Items");
?>

Be aware that simply because you can <?php $dom->addChild();?> doesn't mean your XML is valid under simple XML itself:
<?php
$dom=simplexml_load_string("<test></test>");
$dom->addChild("3D","1,2,3");
$xml=$dom->asXML();
echo $xml;
/* echos:
<?xml version="1.0"?>
<test><3D>1,2,3</3D></test>
*/
$dom=simplexml_load_string($xml);
/*
generates a whole lots of warnings,
and refuses to create an object.
*/
?>
Same in PHP 5.3 and 5.4

This method returns a reference to the specific SimpleXMLElement.
If you use:
<?php
  $xml= new SimpleXMLElement('<root></root>');
  $xml->father['name']= 'Fathers name'; // creates automatically a father tag with attribute name
  $son= $xml->father->addChild('son'); // uses the first father tag
  $son['name']= 'first son';
  $otherSon= $xml->father->addChild('son'); // uses the first father tag but now, in a second son tag
  $otherSon['name']= 'second son';
  
  echo htmlentities($xml->asXML());
?>
The result will be
<root>
  <father>
    <son name='first son' />
    <son name='second son' />
  </father>
</root>
So, once you change something to the just added child, you are actually accessing the element inside the SimpleXMLElement as a reference.

If you're looking for a way to append children you may be interested in this:
<?php
$x = new SimpleXMLElement('<root name="toplevel"></root>');
$f1 = new SimpleXMLElement('<child pos="1">alpha</child>');
$f2 = new SimpleXMLElement('<child pos="2">beta</child>');
$f3 = new SimpleXMLElement('<child pos="3">gamma</child>');
$x->{$f1->getName()} = $f1;
$x->{$f2->getName()}[] = $f2;
$x->{$f3->getName()}[] = $f3;
echo 'count child=',$x->count(),"\n";
echo $x->asXML();
foreach ( $x->children() as $foo )
{
  var_dump($foo);
}
?>

<?php
class MySimpleXMLElement extends SimpleXMLElement
{
  /**
   * Add SimpleXMLElement code into a SimpleXMLElement
   *
   * @param SimpleXMLElement $append
   */
  public function appendXML($append)
  {
    if ($append) {
      if (strlen(trim((string)$append)) == 0) {
        $xml = $this->addChild($append->getName());
      } else {
        $xml = $this->addChild($append->getName(), (string)$append);
      }
      foreach ($append->children() as $child) {
        $xml->appendXML($child);
      }
      foreach ($append->attributes() as $n => $v) {
        $xml->addAttribute($n, $v);
      }
    }
  }
}
?>